Can biventricular pacing (Biventricular Pacing) reduce ventricular tachycardia (VT)?

Biventricular Pacing for Reducing Ventricular Tachycardia

Biventricular pacing can significantly reduce the incidence of ventricular tachycardia (VT) in selected patients with heart failure, particularly those with left ventricular dysfunction, intraventricular conduction delay, and QRS prolongation.

Mechanism and Evidence

Biventricular pacing (cardiac resynchronization therapy or CRT) works by synchronizing the contraction of the left ventricle, which can:

• Improve cardiac hemodynamics and pump function 1
• Increase left ventricular ejection fraction 1
• Reduce mechanical dyssynchrony that may trigger arrhythmias 1
• Reverse adverse cardiac remodeling 1

The Ventak CHF trial demonstrated that patients receiving biventricular pacing had significantly fewer episodes requiring tachycardia therapy compared to periods without pacing (16% vs 34%, p=0.035) 2. This suggests that CRT not only improves heart failure symptoms but also reduces arrhythmic events.

Patient Selection for CRT to Reduce VT

The strongest evidence supports CRT in patients with:

1. Heart failure with reduced ejection fraction:

   • LVEF ≤35% 1
   • NYHA functional class III-IV symptoms 1
   • QRS duration ≥120 ms (strongest evidence for ≥150 ms) 1
   • Left bundle branch block pattern 1

2. Patients with conventional pacing indications:

   • Those requiring high percentage of ventricular pacing
   • Patients with existing right ventricular pacing who have developed LV dysfunction 1

Implementation Considerations

When implementing biventricular pacing to reduce VT:

• Lead placement is critical: Optimal positioning of the left ventricular lead is essential for maximizing resynchronization and reducing arrhythmic events
• Avoid right ventricular pacing in heart failure patients with LV dysfunction, as it can induce dyssynchrony 1
• Consider CRT-D (with defibrillator) rather than CRT-P (pacemaker only) for patients with high risk of sudden cardiac death 1
• Beta-blocker therapy can be better tolerated with CRT, allowing for improved medical management 1

Special Situations

Refractory VT

For patients with refractory VT despite standard CRT:

• Consider dual-site left ventricular pacing plus biventricular pacing as demonstrated in case reports 3
• This approach may provide an alternative strategy when conventional treatments fail

VT Triggered by CRT

In rare cases, CRT may actually trigger VT 4. If this occurs:

• Catheter ablation may be necessary to target the arrhythmogenic focus
• After successful ablation, CRT can often be continued without recurrence of VT

Limitations and Caveats

• Not all patients respond to CRT (non-responder rate ranges from 20-40%) 1
• Patients with permanent atrial fibrillation may have suboptimal benefit unless AV node ablation is performed to ensure adequate biventricular capture 1
• Complications of CRT implantation include lead dislodgement, infection, and coronary sinus dissection 5
• The value of biventricular pacing without additional ICD support for the reduction of sudden death remains controversial 1

In conclusion, biventricular pacing represents an important therapeutic option for reducing ventricular tachycardia in appropriately selected patients with heart failure, particularly those with ventricular dyssynchrony evidenced by QRS prolongation and left bundle branch block pattern.